U.S. Pat. Nos. 4,964,890, 4,982,014, and 5,210,328 disclose methods of making BPTMC by condensing phenol with TMC in the presence of an acid catalyst. An organosulfur cocatalyst may also be used. These disclosures use TMC and ether ketones. They do not use the starting materials of applicants' disclosure.
Ketones are not the only known starting materials for making bisphenols. U.S. Pat. No. 4,201,878 teaches a method using ketals and alkenyl ethers. However, the U.S. Pat. No. '878 disclosure only includes ketals of unbranched cyclic ketones. The rapid formation of BPTMC in the present invention is surprising, and it is not predictable from the disclosure of the U.S. Pat. No. '878.
The three methyl groups of TMC affect the properties of materials containing TMC in ways that are difficult to predict. For example, cyclohexanone and phenol form bisphenol Z much faster than TMC and phenol form BPTMC due to interference from the methyl groups on TMC [see Makromol. Chem., Rapid Commun., Vol. 12, pp. 95-99 (1991) and Angew. Chem. Int. Ed. Engl., Vol. 30, pp. 1598-1610 (1991)]. Similarly, the properties of bisphenol Z polycarbonate cannot be used to accurately predict the properties of BPTMC polycarbonate. U.S. Pat. No. 5,210,328 shows that TMC and 4-tert-butylcyclohexanone respond differently to water during condensation with phenol.
In U.S. Pat. No. 3,919,330 a reference is made to U.S. application Ser. No. 432,376 filed Jan. 10, 1974 in which bisphenol-A is reported to have been disclosed as made from the ketal of acetone and ethylene glycol. Again, the trimethyl structure of TMC creates unique physical and chemical properties. Formation of BPTMC is not predictable or obvious from the disclosure of bisphenol-A formation from ketal or vinyl ether starting materials. Additionally, applicants know of no precedent for the formation of BPTMC or any other bisphenol from hemithioketal starting materials.